To provide information on the basic process of ATP-transphosphorylation, studies are being conducted: (a) To continue the comparison of the isoenzymes for calf, rabbit, and man of ATP-creatine transphosphorylase, of ATP-AMP transphosphorylase from rabbit and calf muscle and liver, and of thiamine pyrophosphokinase from porcine brain by physical, chemical and kinetic means; (b) To shed light on the basic structures of the intact two-chain molecule of the ATP-creatine transphosphorylases (e.g., the hybrid species) and of the native single-chain molecule of the ATP-AMP transphosphorylase; (c) To elucidate the primary structures of the ATP-creatine transphosphorylases; (d) To correlate chemical structure and enzyme function of the ATP-creatine transphosphorylases and of the ATP-AMP transphophorylases, especially with the aid of synthetic peptide systems for binding of the substrates and also with the aid of immunological probes; (e) To complete the comparison of the ATP-creatine transphosphorylases isolated from dystrophic tissues with their normal human counterparts, and to explore with immunological assays the isoenzyme distribution during embryogenesis, and thereby to provide clues as to the nature of this disorder; (f) To re-explore the association-dissociation behavior of the NTP-NDP transphosphorylase (nucleoside diphosphokinase) with attention to effects on enzyme kinetics and covalent (phosphoryl) intermediates, and to initiate studies on its primary structure. As part of a progrm on NADP-associated reactions: (a) The controlled use of EDTA3- which modifies the dissociation-association equilibria of the glucose 6-phosphate dehydrogenase from brewers' yeast has permitted a simplified approach to studies on its catalytic mechanism through direct steady-state kinetic measurements on the active, two-chain enzyme species. Studies are in progress which may correlate physical changes (the association-dissociation behavior) with enzyme function and its essential side-chain groups with catalytic activity and substrate binding. (b) Studies on the newly isolated ale-yeast NADPH-cytochrome c reductase are being extended to include its physical, chemical and kinetic chracterization, with special emphasis on the role of the semi-quinone of FAD in its mech (Text Truncated - Exceeds Capacity)